GENEVA -- Illegal fishing has critically depleted global stocks of tuna and some species are at high risk of commercial extinction, environmental group WWF said on Monday.

WWF, formerly known as both the World Wildlife Fund and the Worldwide Fund for Nature, said that Atlantic bluefin, used in sushi and sashimi, had been massively overfished, and other tuna species including Atlantic albacore were critically endangered.

The Swiss-based group faulted regulators for failing to established quotas and allowing "far too many boats" to chase an increasingly vulnerable sea population, warning that bluefin could become so sparse it will be commercially unviable as catch within a few years.

"Many governments are routinely ignoring scientific advice, failing to implement the available conservation and management measures, turning a blind eye to illegal fishing and not prosecuting those who flout the rules," said Simon Cripps, director of WWF's global marine programme.

The world's five major tuna management groups -- regional clusters of governments known as Regional Fisheries Management Organisations -- are meeting this week in Kobe, Japan, to discuss problems facing the industry.

WWF spokeswoman Sarah Bladen said it was vital for governments to strengthen their enforcement of tuna quotas, which are set each year, and prosecute those who flouted the rules.

Countries should also encourage measures to reduce the large numbers of sharks, marine turtles, seabirds and dolphins ensnared in tuna hooks and nets, Bladen said -- such as shark-repelling magnets and plastic "sea scarecrows" that ward off albatrosses.